1. Field of the Invention and Related Art Statement
This invention relates to an endoscope having a tip covered with a soft material.
Recently, there is extensively used an endoscope whereby an organ or the like within a body cavity can be observed by inserting an elongated insertable part into the body cavity or various curing treatments can be made by using a treating tool inserted through a treating tool channel as required.
Various electronic endoscopes wherein such solid state imaging device as a charge coupled device (CCD) is used for an imaging means have been suggested. Such electronic endoscope has advantages that its resolution is higher than of a fiberscope, it is easy to record and reproduce a picture image and such picture image treatments as the enlargement of a picture image and the comparison of two pictures are easy.
Now, in the above mentioned endoscope, a hard tip part is provided on the tip side of the insertable part. This tip part is provided with a tip body made of a hard member. An objective lens system or the like is contained and fixed in this tip body. A tip part covered with an insulating cover for electric safety is disclosed, for example, in Japanese Patent Publication No. 22566/1986. Such comparatively hard (respectively of Rockwell hardnesses M63, M80, M90 and M90) plastics as polycarbonate, polyacetal, polysulfone and modified PPO (nonyl) or so-called engineering plastics have been used for the above mentioned insulating cover.
However, there are problems that, if the above mentioned tip part is formed of a hard member or is covered with a hard plastic, when this tip part is struck, the shock will be likely to be transmitted to the interior and, by this shock, the cementing part of an objective or the like contained in the above mentioned tip part will be peeled off to leak water or for the visual field, a solid state imaging device or the like in an electronic endoscope will be damaged or a wiring will be cut off.
By the way, an endoscope in which the tip part is covered to the midway with a soft cover member is disclosed in U.S. Pat. No. 4,290,421. However, this cover member does not cover the corner part of the tip surface and therefore has the same defects as of the above described prior art example.